docs: def get_user_if_exists(strategy, details, user=None, *args, **kwargs):
      """Return a User with the given username iff the User exists."""
      if user:
          return {'is_new': False}
      try:
          username = details.get('username')
  
          # Return the user if it exists
          return {
              'is_new': False,
              'user': User.objects.get(username=username)
          }
      except User.DoesNotExist:
          # Fall to the default return value
          pass
  
      # Nothing to return since we don't have a user
      return {}